I haven't done this myself, but read an interesting post once about a chap who uses a drywall bucket ,half filled with sand, pea gravel, water and borax. He sticks it in a cheapo small cement mixer (HF,IIRC), and runs it for a few minutes to as much as an hour. He tumbled all sorts of things in it.
You could probably set the bucket on the ground and rock/poll it back and forth with your foot while enjoying a beer and get similar results.